Holt CA Course 1

7-1 Mean, Median, Mode, and Range

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Holt CA Course 1

7-1 Mean, Median, Mode, and Range

Warm UpOrder the numbers from least to greatest.

1. 8, 6, 25, 7, 4, 12

2. 60, 11, 27, 45, 32

Divide

3. 720 ÷ 4 4. 760 ÷ 10

4, 6, 7, 8, 12, 25

11, 27, 32, 45, 60

180 76

Holt CA Course 1

7-1 Mean, Median, Mode, and Range

SDAP1.1 Compute the range, mean, median, and mode of data sets.

California Standards

Holt CA Course 1

7-1 Mean, Median, Mode, and Range

Players on a volleyball team measured how high they could jump. The results in inches are recorded in the table.

One way to describe this data set is to find the mean. The mean is the sum of all the items divided by the number of items in the set. Sometimes the mean is also called the average.

13 23 21 20 21 24 18

Holt CA Course 1

7-1 Mean, Median, Mode, and Range

Some other descriptions of a set of data are called the median, mode, and range.

• The range is the difference between the least and greatest values in the set.

• The median is the middle value when the data are in numerical order, or the mean of the two middle values if there are an even number of items.

• The mode is the value or values that occur most often. There may be more than one mode for a data set. When all values occur an equal number of times, the data set has no mode.

Holt CA Course 1

7-1 Mean, Median, Mode, and Range

Vocabulary

meanmedianmoderange

Holt CA Course 1

7-1 Mean, Median, Mode, and Range

Additional Example 1A: Finding the Mean of a Data Set

Depths of Puddles (in.)

5 8 3 5 4 2 1

5 + 8 + 3 + 5 + 4 + 2 + 1 = 28

28 ÷ 7 = 4

The mean is 4 inches.

Add all values.

Divide the sum by the number of items.

Find the mean of each data set.

Holt CA Course 1

7-1 Mean, Median, Mode, and RangeAdditional Example 2: Finding the Mean, Median, Mode, and

Range of a Data Set

range: 15 – 11 = 4

mean: 12 + 11 + 14 + 15 4

= 13

median: 11, 12, 14, 15

12 + 14 2

= 13

mode: none

The mean is 13 cars washed; the median is 13 cars washed; there is no mode; and the range is 4 cars washed.

Write the data in numerical order: 11, 12, 14, 15. There are an even number of items, so find the mean of the two middle values.

Find the mean, median, mode, and range of the data set.

Car Wash Totals

6th Grade 12 7th Grade 11

8th Grade 14 9th Grade 15

Add all the values. Divide the sum by the number of items.

No value occurs most often.Subtract the least value from the greatest value.

Holt CA Course 1

7-1 Mean, Median, Mode, and Range

Check It Out! Example 1A

Find the mean of each data set.

Rainfall per month (in.)

1 2 10 2 5 6 9

1 + 2 + 10 + 2 + 5 + 6 + 9 = 35

35 ÷ 7 = 5

The mean is 5 inches.

Add all values.

Divide the sum by the number of items.

Holt CA Course 1

7-1 Mean, Median, Mode, and RangeCheck It Out! Example 2

range: 22 – 11 = 11

mean: 17 + 11 + 22 + 14 4

= 16

median: 11, 14, 17, 22

14 + 17 2

= 15.5

mode: none

The mean is $16; the median is $15.50; there is no mode; and the range is $11.

Write the data in numerical order: 11, 14, 17, 22. There are an even number of items, so find the mean of the two middle values.

Find the mean, median, mode, and range of the data set.

Bake Sale Profits ($)

6th Grade 17 7th Grade 11

8th Grade 22 9th Grade 14

Add all the values. Divide the sum by the number of items.

No value occurs most often.

Subtract the least value from the greatest value.

Holt CA Course 1

7-1 Mean, Median, Mode, and RangeLesson Quiz

Use the following data set: 18, 20, 56, 47, 30, 18, 21.

1. Find the range. 2. Find the mean.

3. Find the median. 4. Find the mode.

5. Bonnie ran a mile in 8 minutes, 8 minutes, 7

minutes, 9 minutes, and 8 minutes. What was

her mean time?

38 30

21 18

8 minutes

Holt CA Course 1

7-1 Mean, Median, Mode, and RangeAdditional Example 1B: Finding the Mean of a Data

Set

96 + 75 + 84 + 7 = 262

262 ÷ 4 = 65.5

The mean is 65.5 points. The average number of points scored is 65.5.

Add all values.

Divide the sum by the number of items.

Find the mean of each data set.

Number of Points Scored

96 75 84 7

Holt CA Course 1

7-1 Mean, Median, Mode, and RangeCheck It Out! Example 1B

Find the mean of each data set.

53 + 26 + 47 + 12 = 138

138 ÷ 4 = 34.5

The mean is 34.5 points. The average number of points scored is 34.5.

Add all values.

Divide the sum by the number of items.

Number of Points Scored

53 26 47 12